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InterviewSolution
| 1. |
ohm's low( from first principle method) |
| Answer» <p>OHM’S LAW</p><p>Statement:– Ohm’s law states that the current (I) flowing through a conductor is directly proportional to the potential difference (V) across the ends of the conductor,provided physical conditions of the conductors such as temperature,mechanical strain etc. Are kept constant i.e. IαV</p><p>Or VαI or V= RI</p><p>Or V/I=R=a constant</p><p>Where R is known as resistance of the conductor . It depends upon the length ,shape and the nature of the material of the conductor. The variation between potential difference (V) and current (I) through a conductor is a straight line.</p><p>Deduction of Ohm’s Law:</p><p>As drift velocity is given by Vd=eEt/m</p><p>But Electric field across the conductor of length l is</p><p>E=V/l</p><p>Thus Vd=e V/ml</p><p>Also, I=Anevd</p><p>By putting value of vd in the equation of I (equation 1 of relation of the current and drift velocity),we get</p><p>I=Ane(eV/ml)=(Ane2/ml)V</p><p>Or V/I=ml/Ane2=R</p><p>Where R is a constant for a given conductor. It is known as the resistance of the conductor.</p><p>Thus V=RI</p><p>This is Ohm’s law.</p> | |